A differential-pressure flow meter is a device for measuring a flow rate by converting a difference in fluid pressure between the front and rear sides of an orifice member to a flow rate. The differential-pressure flow meter uses, for example, pressure sensors configured to measure variations in the strain of diaphragms with pressure and to feed the resulting electrical signals to an external controller.
Referring to FIG. 20B, for example, a differential-pressure flow meter 1 installed somewhere along a pipe P requires pressure sensors 3A and 3B at two positions upstream and downstream of an orifice member 2. The pair of pressure sensors 3A and 3B each accommodate a control circuit board and must therefore be separately wired and connected to a controller CR. In addition, for operational control of a semiconductor manufacturing apparatus using the flow rate measured with the differential-pressure flow meter 1, for example, wiring for outputting the measured flow rate must be provided between the controller CR, which is required for each differential-pressure flow meter, and an apparatus control sequencer CU for controlling various operations of the semiconductor manufacturing apparatus (for example, see Patent Document 1).
A semiconductor manufacturing apparatus often uses many differential-pressure flow meters 1 arranged in parallel, as shown in, for example, FIG. 20A.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. HEI-6-213694